firefox: Update version from 50.0.2 to 50.1.0

Release notes [1]:

> Version 50.1.0, first offered to Release channel users on December 13,
> 2016
>
> fixed: Various security fixes [2][3]

Add fixes for MFSA 2016-95, also known as:

CVE-2016-9894, CVE-2016-9899, CVE-2016-9895, CVE-2016-9896,
CVE-2016-9897, CVE-2016-9898, CVE-2016-9900, CVE-2016-9904,
CVE-2016-9901, CVE-2016-9902, CVE-2016-9903, CVE-2016-9080,
CVE-2016-9893.

[1] https://www.mozilla.org/en-US/firefox/50.1.0/releasenotes/
[2] https://www.mozilla.org/en-US/security/known-vulnerabilities/firefox/#firefox50.1
[3] https://www.mozilla.org/en-US/security/advisories/mfsa2016-94/

firefox.be0

@@ -2,7 +2,7 @@
 
 #export BEE_TMP_TMPDIR=/dev/shm BEE_TMP_BUILDROOT=/dev/shm/bee-root BEE_MAKEFLAGS='-j80'
 
-# BEE_VERSION firefox-50.0.2-0
+# BEE_VERSION firefox-50.1.0-0
 
 SRCURL[0]="https://ftp.mozilla.org/pub/firefox/releases/${PKGVERSION}/source/firefox-${PKGVERSION}.source.tar.xz"